Does The Enterprise Orbit

I've come to believe that in Kirk's time the Enterprise wasn't always orbiting the planet, but was instead hovering on it's impulse engines above a fixed point on the planet's surface. For example Assignment: Earth, the Enterprise was stationary two hundred miles directly above the New York City. At that altitude she would have been orbiting at five miles a second, but at a hover she is moving forward at only at a third of a mile per second, matching the city below her. Impulse engines that could propel the ship at hundreds of gees through space can easily provide one continuous gee to hover.

Click to expand...

Nothing is more subtle than two thermonuclear engines spitting out enough hot reaction mass to keep a million ton vessel stationary over a major metropolitan area during the Cold War.

Click to expand...

I always assumed that the impulse (Fusion) engines were only used for sublight travel. Maybe in a "powered" orbit the starship uses the warp field or some other energy field to negate gravity so the ship can "park" anywhere it wants in orbit. Anti-matter is only used to power the warp engines, not used for thrust to propel the ship so there would be no large radiation signature coming from the ship since the warp engines are fully contained. Just my 2 cents.

Is there anything in canon to support or refute the notion that a space vessel's "orbit" of a given planet could be "powered" for one instance and "natural" for the next? In other words, could the Enterprise and other vessels in TOS/TNG/etc be employing different "orbit" techniques depending on the mission and the skipper's discretion?

Click to expand...

The orbit in "This Side of Paradise" must be a natural one as there's no mention of it decaying anytime soon. Kirk says he could stay aboard, but not pilot the Enterprise. Ditto Exeter's in "Omega Glory". She'd been there for at least six months. "Court Martial" seems to show a powered one, otherwise Finney's sabotage of the engines would be no immediate threat. The choice must be the captain's, dependent on the mission.

According to this Memory Alpha article, the Enterprise orbited Excalbia at an altitude of almost 643.5 miles. If we assume that this orbit was a "powered" one, and that it would be typical of "powered" orbits, would it require huge amounts of energy to sustain? I could see this notion of "powered" orbits being used, but I would think it would have to be arranged to avoid excessive power consumption.

According to this Memory Alpha article, the Enterprise orbited Excalbia at an altitude of almost 643.5 miles. If we assume that this orbit was a "powered" one, and that it would be typical of "powered" orbits, would it require huge amounts of energy to sustain? I could see this notion of "powered" orbits being used, but I would think it would have to be arranged to avoid excessive power consumption.

Click to expand...

Momentum does part of the work of keeping the ship from falling out of orbit. The higher the orbit, the less power is required. How much power must be applied depends on the planets's rotation you are matching. Faster rotation means less power needed. You could think of it as flying backward within your orbit in relation to the advance of the area you want to scan, since an unpowered orbit would take you around too fast in most cases. And you orbit above the planet's equator, maintaining the desired distance from the spot of interest, albeit at an angle. If you don't need to stay in sight of a certain spot, you can move to an orbit 600 miles above the surface and coast until the plot thickens.

The Space Shuttle orbiter flies forward within its initial orbit to catch up with the ISS but uses little power to do that and usually takes many hours (many trips around the world)
to match the orbit of the ISS.

I aways assumed a powered orbit, given certain references to short orbital periods and the ability ot "hang" over a given ground site for long periods of time.

Click to expand...

The "hang" could be caused by apoapsis dwell if the Enterprise employs highly elliptical (i.e., Molniya-Class) satellite orbits in order to stay above the landing party's horizon for the maximum possible time during every orbital period in the event an emergency beam-out is required. Of course, this is highly dependent on the subject planet's diameter, gravitational potential and sidereal rotation rate, although one may propose that in a majority of cases the space vehicle's orbit is artificially precessed by firing the impulse engines briefly at periapsis in order to keep the apoapsis directly over the landing party's position during each pass. OTOH, an idling warp drive may be able to sufficiently amplify the Lense-Thirring (i.e., relativistic "gravito-magnetic" frame dragging) effect when the orbit's inclination is close to equatorial for the same purpose depending upon which propulsion system is more energy efficient for a particular planet/orbit combination.

1) "Orbit" today is valid parlance for the pattern an aircraft maintains, for example when aiming a radar at the ground below, or waiting for its turn to land, or waiting for a chance to provide fuel to other aircraft. Thus, if Kirk orders a stationary orbit above London, there's nothing semantically wrong with it, even though "stationary orbit" does have other usages in aeronautics jargon besides "staying put above said spot".

2) I think we can all agree that a starship would be able to maintain a steady one gee of acceleration (and thus hover over any given spot) for at least a couple of months if not years. That is, the ship isn't likely to run out of fuel or energy in that time, and the engines supposedly don't require all that much "must take 'em offline" maintenance. Perhaps impulse engines do require some sort of propellant that would run out if the ship wasn't allowed to take short breaks for replenishment, though? Difficult to tell, since their actual method of operation has been kept hidden in aired Trek.

3) The effects of impulse hovering on the spot beneath might not be all that severe when we consider that the shipwrights would do everything in their power to minimize the "impulse signature" anyway, for tactical reasons.

“Orbit” today is valid parlance for the pattern an aircraft maintains, for example when aiming a radar at the ground below, or waiting for its turn to land, or waiting for a chance to provide fuel to other aircraft.; anyway, for tactical reasons.

Click to expand...

Oh? When did they start using that term? I always thought it was called a “holding pattern.”

An aircraft flying in a big circle while waiting to land isn't orbiting anything. It's just flying in a big circle.

Is there anything in canon to support or refute the notion that a space vessel's "orbit" of a given planet could be "powered" for one instance and "natural" for the next? In other words, could the Enterprise and other vessels in TOS/TNG/etc be employing different "orbit" techniques depending on the mission and the skipper's discretion?

Click to expand...

The orbit in "This Side of Paradise" must be a natural one as there's no mention of it decaying anytime soon. Kirk says he could stay aboard, but not pilot the Enterprise. Ditto Exeter's in "Omega Glory". She'd been there for at least six months. "Court Martial" seems to show a powered one, otherwise Finney's sabotage of the engines would be no immediate threat. The choice must be the captain's, dependent on the mission.

Click to expand...

"Mirror, Mirror" seems to acknowledge a normal low orbit, since they mention cities coming in and out of targeting range as they orbit.

It gets even more complicated when we hear about starships orbiting space stations like DS9 and K7. I had thought for a while that these stations might have their own artificial gravity generators specifically designed to allow ships to orbit them the way they would a planet, but if you take "orbit" to be a more generic term it could refer to anything from stationkeeping patterns to a complicated arrangement involving tractor beams and impulse engine counterthrust.